Recently, in a magnetic recording/reproducing device, such as a magnetic recording device, improvement of a thin film magnetic head and a magnetic recording medium is in demand in association with high recording density.
Thin film magnetic heads can be classified roughly into a so-called longitudinal magnetic recording system and a perpendicular magnetic recording system depending on the recording system. The longitudinal magnetic recording system is a system for forming the direction of recording magnetization in the longitudinal direction within the recording surface of a magnetic recording medium and recording data, and the perpendicular magnetic recording system is a system for forming the direction of recording magnetization in the perpendicular direction relative to the recording surface of the magnetic recording medium and recording data.
A thin film magnetic head of the perpendicular magnetic recording system can record data with a recording density which is dramatically higher than that of the longitudinal magnetic recording system. In addition, after data is recorded, the magnetic recording medium is hardly affected by thermal fluctuation. Consequently, the reliability of the data recorded with high recording density using the perpendicular magnetic recording system thin film magnetic head is extremely high.
The perpendicular magnetic recording system thin magnetic head, which is extremely advantageous for high recording density, constitutes the major portion of such systems in the technical field of magnetic recording, and further higher recording density is in demand for the thin film magnetic head. In order to satisfy such demand, it is necessary to improve the writing characteristics of the thin film magnetic head, and to prevent adjacent track erasure (ATE) or wide area track erasure (WATE) when data is recorded to the magnetic recording medium using a perpendicular magnetic recording system thin film magnetic head.
For the purpose of improving the writing characteristics and preventing adjacent track erasure or wide area track erasure (ATE or WATE), for example, in U.S. Pat. No. 8,238,056, as shown in FIG. 8, a thin film magnetic head 1′ is disclosed that includes a main magnetic pole layer 21′ having a tilted surface where its thickness (thickness in a medium traveling direction) can be gradually reduced toward a medium opposing surface and a trailing shield 23′ positioned at the trailing side of the main magnetic pole 21′.
In the thin film magnetic head 1′, if it is miniaturized in order to respond to the demand for further higher recording density, and the thickness TH of the trailing shield 23′ in the height direction becomes smaller, saturation of magnetic flux in the trailing shield 23′ occurs, and adjacent track erasure or wide area track erasure (ATE or WATE) may not be effectively suppressed.